


Size Doesn't Matter

by SpyroForLife



Category: Invader Zim
Genre: Alien Biology, Anal Sex, Antennae Stimulation, Begging, Biting, Bottom Dib - Freeform, Dirty Talk, Kink Discovery, M/M, Master/Pet, Penis humiliation, Plot What Plot/Porn Without Plot, Rough Sex, Size Difference, Teasing, Top Zim
Language: English
Status: Completed
Published: 2020-10-16
Updated: 2020-10-16
Packaged: 2021-03-09 04:14:58
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,906
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27048556
Author URL: https://archiveofourown.org/users/SpyroForLife/pseuds/SpyroForLife
Summary: It's what you do with it, as the old saying goes. And when Dib underestimates Zim based on his size, Zim teaches him a lesson he won't soon forget.
Relationships: Dib/Zim (Invader Zim)
Comments: 4
Kudos: 170





	Size Doesn't Matter

“Is that it?” The words left Dib’s mouth almost automatically and he was met with a confused stare.

“Er, yes?” Zim replied, raising a brow. “This is my breeding spike, as you requested.”

Dib spent a few moments looking at the tentacle-like organ that had emerged from between Zim’s legs, wiggling and covered in fluid. It was almost everything he had hoped for when Zim agreed to sleep with him… there was just one small problem.

Literally.

“Is there a problem?” Zim asked haughtily.

“Well, oh how do I say this… I guess I was expecting you to be bigger,” Dib replied.

Zim blinked. “Bigger?”

“Yeah, you know. Down there.” Dib gestured to the tentacle.

“This is more than adequate for irkens of my height!”

“Yeah, guess it would be… still, I guess I was hoping you would have some ridiculously huge alien cock.”

Zim huffed in annoyance. “Then you shouldn’t have made dumb assumptions. This is what I have.”

“No kidding.” Dib kept checking him out. Yep, as nice as Zim looked down there, that tentacle was definitely barely hitting three inches in length. And that was being generous. He felt bad about being so judgmental but well, when have the two of them not mocked each other? Zim didn’t seem too offended, at least. He mostly just looked annoyed.

“So are you wishing to back out of mating with me due to this?” Zim asked.

Dib looked up at his face. The other’s cheeks were flushed pink and Dib could tell he was already aroused from anticipation. Dib’s cock ached with want. “No, of course not, I want to do it.”

“And you still want me to take the dominant position, despite finding me inadequate?”

“Come on, I didn’t say that, I was just surprised okay? You’re small compared to a human, but that’s fine because proportionally you look great, I just… do kinda feel bad because it might take a lot of work for you to get me off…”

Zim rolled his eyes while Dib was babbling and got between his legs, spreading them open. Dib had told him he had prepared himself before this, so he figured he might as well get started. “Shut up, I’m going to fuck you now.”

The abruptness took Dib by surprise, but then he chuckled and rested back, crossing his arms behind his head and lifting his hips for the other. “Alright then, give it to me, tiny.”

Zim growled and pressed himself to Dib’s entrance, tip circling it and coating it thoroughly with lubricant before thrusting inside.

“Ohh yeah, that’s it… that feels so weird.” Dib wiggled a bit against him.

Zim adjusted his stance a bit, then took a few moments to get used to how Dib’s body felt. It was so warm around him. Warm and snug, seeming to grip him from every angle, and he felt amazing. It’s been a long time since Zim has been able to mess around with someone and he almost never got to be on top like this, but he knew what to do.

He first explored what he could of Dib’s insides, testing different spots and seeing how the other responded.

“Aah, that’s so weird how it squirms around like that…” Dib’s back lifted a bit. Zim may not be large but that very alien way he probed at him was definitely already doing it for him. He felt like even more of a jerk for teasing him. Dib would be a liar if he said he wasn’t a size queen but that was no reason to make Zim feel bad.

But it seemed Zim was determined to give him a good time anyway.

After a few moments, Zim glanced across a spot that got a much stronger reaction, Dib arching and letting out a breathy gasp. Zim noted this with fascination, looking down and seeing some precum bead at the other’s tip. Then he looked back at his face.

Dib relaxed, chuckling and meeting Zim’s eyes. “Well, you found the prostate.”

“The what?”

“It’s this gland, you can stimulate it through the rectal wall and it feels fucking amazing.”

“I see. That’s very useful!”

“Yeah, I guess I didn’t think about how it’s only a couple inches in so even you would have no problem hi- oh _hh Zim!_ ” Dib cried out as Zim latched his claws sharply into his hips and began thrusting into him, roughly hitting his sweet spot and immediately filling him with bliss.

Zim’s aim was perfect and it only seemed to take a few moments of hard, on point thrusts before Dib was coming, his vision whiting out as he did.

When he came down from the high, he was shaking and panting, body glowing with pleasure. He swallowed, opening his eyes and glancing down. He had come a good way up his front, some of the cum even reaching his chest. Then he looked at Zim, who was still buried completely in him but had stilled, and he was giving him the most smug smile Dib has ever seen on his face.

“So, what was that about needing a lot of work to get you off?” Zim asked.

Dib blushed. “That was just… I mean…” It was hard forming words right now. “I’m sensitive, okay?”

“Uh-huh.”

“I've never... never had someone who felt like you before.”

“Right.”

“I’m sure if I get used to it, it’ll take longer for me to finish…”

Zim smirked and began moving again, making Dib yelp. He couldn’t help it; Zim just felt so good, the ridges of his length gliding so perfectly against his skin as he rocked in and out, and the way he steadily pounded his sweet spot… without compare.

Dib wrapped his legs around Zim’s waist and just gave in to his pace, following with short thrusts of his own hips, feeling himself quickly grow hard again.

Zim was very pleased at how he had such a tall creature obeying him like this. This sort of thing would never happen back on Irk… the reversal of power dynamics was such a turn on. He moaned as his pleasure built, the sensations running up and down his back, heat pooling between his thighs.

Unable to keep quiet, even during this, he groaned through gritted teeth, “Feels good, huh, stink beast? You nngh, underestimated me… bet you’ll never make that mistake again, huh?”

“N-no, never,” Dib replied. He moaned when Zim leaned over him, stomach pressing to his erection. He felt the tickle of antennae against his chest, then Zim was placing a light kiss to his skin.

“Yeah, you’ve learned your lesson.” Zim’s voice had dropped low, taking on a rougher timbre in his arousal. “Look at you squirming under me. You love being filled with me, hm? Say it.”

“Yes, I love being filled with you,” Dib said, close to losing it again.

“That’s right. And you want to be filled with my seed, yes?”

Dib bucked, a whimper escaping him. “Ohh, fuck…”

“Answer me,” Zim ordered.

He felt Dib harden under him and the other exclaimed, “Yes! Yes, please, come in me!”

“Such a disgusting creature. But I’m feeling merciful. Your master will give you what you want.” Zim moved more firmly, purposely letting himself miss the prostate every other thrust or so, until he could hear the other whining with frustration. “Oh? What is it, pet?”

Dib’s dick twitched at the title and he briefly swore, not expecting that to get to him so much. Then he said, “You keep… keep missing…”

“Am I? Aw, I must be getting a little tired, after all it takes so much work to satisfy you…”

“I was wrong, okay, I don’t need a lot, please…”

“Hm? What are you saying, pet? Are you saying you’re actually quite easy to get off?”

“I didn’t… didn’t think I was, but you just, ah… you feel so good…”

Zim was reveling in that desperate tone. “Or perhaps I’m just so superior to any human or toy you’ve ever had inside you.”

Dib was close to sobbing when Zim actually slowed. He squeezed him with his thighs, trying to get him to speed back up. “Zim, Zim please, more…”

“I want you to say it. Say you were a fool to misjudge me and that I’m the best you’ve ever had.”

Dib wasn’t in any place to argue. “I was a fool, I was so stupid, I shouldn’t have assumed… you feel so good, you’re better than anyone else I’ve been with…”

“That’ll do. Now you make sure you remember that.” Zim bit down on Dib’s chest and Dib’s hands went to his antennae. Zim paused but Dib merely stroked them, running his thumbs against the bases, and the currents of pleasure that ran down them mixed so perfectly with what he was already feeling.

He purred and kept thrusting, again hitting the sweet spot with each movement, and he was rewarded with his partner crying out his name, body tensing. Zim kissed the spot where he had bitten Dib and then lifted his head, focused on the other’s face.

Dib looked so good with his eyes closed and head thrown back, mouth open as he panted and begged softly.

Zim has never found him more attractive. He kept his eyes on him as he moved, Dib’s expressions only adding to his pleasure, but then Dib circled his thumbs just right along his antennae that he grew overwhelmed.

Zim closed his eyes and hunched over Dib as the sensations all hit the peak, managing a few more thrusts before he was finishing. He came right against that sweet spot and opened his eyes in time to see Dib finish too, another arc of cum leaving his tip and landing across his stomach and chest. Dib let out a surprisingly soft whimper too, which made Zim smile, finding it cute.

“Good boy,” Zim said, patting his hip and then withdrawing. He crawled up to lay next to Dib, avoiding the mess on his front and instead just resting his chin on his shoulder. “How was that?”

Dib was still catching his breath, but he opened his eyes and said, “Good. Very good, holy shit.”

“I’m glad to hear that. You learned a valuable lesson today, eh?”

“Oh yeah. Yeah, definitely. Well, a couple lessons, actually.” Dib stroked Zim’s back. “First, I learned that I’m really into being called a pet, didn’t know that about myself…”

Zim snickered.

Dib continued, “And second, yeah, I learned to never judge someone by their size again. That was awesome.”

“Honestly Dib, how long have you known me now? After all this time you should know…” Zim put aside his mild disgust toward Dib’s bodily fluids, swinging himself up onto his chest so he could lean over him, playing with his hair. “My size doesn’t matter. It’s what I do with it that counts. And I will always dominate you. You weak, pathetic creature.”

Dib raised a brow. “This weak, pathetic creature is way taller than you and could drop kick you across the room.”

“But you won’t. Because you recognize my superiority and you like being compliant to me,” Zim bragged.

Dib rolled his eyes. He was in too good of a mood to argue. Besides, Zim was right. He did like submitting to him. And he was already looking forward to doing it again. “Sure, Zim. Whatever you say.”


End file.
